The present invention relates to a socket which permits easy positioning of a plug relative thereto.
FIGS. 1 and 2 show a conventional socket, in which a hollow cylindrical member of metal 10 is received in an annular groove cut in the front of a socket body 11 of an insulating material and contacts 14 are housed in a columnar portion 13 of the body 11 surrounded by the cylindrical member 10. The columnar portion 13 has cut in its peripheral surface positioning grooves 15a, 15b and 15c extending lengthwise thereof. FIG. 3 shows the mating plug to be put in the socket, in which a plug body 16 supports contacts 17 projecting out therefrom and is fixedly held in a hollow cylindrical member of metal 18 surrounding the contacts 17. The cylindrical member 18 has inward protrusions 19a, 19b and 19c (19c not shown) in its forward portion.
The plug can be put in the socket only when the former has been turned to the position where its protrusions 19a, 19b and 19c are aligned with the corresponding positioning grooves 15a, 15b and 15c of the socket, respectively. The forward portion of the cylindrical member 18 of the plug is fitted into the annular groove 12 inside the cylindrical member 10 of the socket, by which the corresponding contacts 14 and 17 of the socket and the plug are brought into engagement with each other.
For example, in the case where the socket happens to be mounted on the back of a device used therewith and hence cannot be seen directly when the plug is put therein, it is necessary to bring the protrusions 19a, 19b and 19c of the plug into alignment with the positioning grooves 15a, 15b and 15c of the socket by blindly turning the plug about its axis while at the same time urging its forward end against the front of the socket. It is difficult, however, to align the axes of the plug and the socket and to turn the plug for rotational angular positioning relative to the socket without causing misalignment therebetween, and consequently, it is hard and time-consuming to put the plug in the socket. In addition, since the plug is turned while being pressed against the socket, the protrusions 19a, 19b and 19c of the plug abrade the peripheral surface of the columnar portion 13 of the resin-made body 11 and powder may sometimes adhere to the contacts, causing bad contact therebetween.